What is the mass percent of water in magnesium chloride hexahydrate? Provide an answer to two decimal places.
The Correct Answer and Explanation is:
To calculate the mass percent of water in magnesium chloride hexahydrate (MgCl₂ · 6H₂O), we need to first determine the molar mass of the compound and then the mass of water within it.
Step 1: Determine the molar mass of MgCl₂ · 6H₂O
- Mg (Magnesium): 24.31 g/mol
- Cl (Chlorine): 35.45 g/mol
- H₂O (Water): 18.015 g/mol (for 1 molecule of water)
Now, let’s calculate the molar mass of magnesium chloride hexahydrate:
- Molar mass of MgCl₂: (24.31) + 2(35.45) = 24.31 + 70.90 = 95.21 g/mol
- Molar mass of 6H₂O: 6 × 18.015 = 108.09 g/mol
So, the total molar mass of MgCl₂ · 6H₂O = 95.21 + 108.09 = 203.30 g/mol
Step 2: Calculate the mass of water in the compound
The mass of water in the compound is simply the mass of 6 molecules of water:
- Mass of water = 108.09 g/mol
Step 3: Calculate the mass percent of water
To find the mass percent of water, divide the mass of water by the total molar mass of the hydrate and multiply by 100: Mass percent of water=(108.09203.30)×100=53.2%\text{Mass percent of water} = \left( \frac{108.09}{203.30} \right) \times 100 = 53.2\%Mass percent of water=(203.30108.09)×100=53.2%
Final Answer:
The mass percent of water in magnesium chloride hexahydrate is 53.20%.
